In recent years, there has been a growing trend toward using minimally invasive surgical techniques to perform heretofore complicated and complex operations. Minimally invasive techniques have therefore been applied to many procedures such as gall bladder removal, operation on the reproductive organs, urological operations, and, more recently, heart valve repair and replacement as well as by-pass operations. Minimally invasive surgery uses only a small incision through which tools are inserted into the patient, with the tool being manipulated from outside the patient. Video is often used so the surgeon can view the surgical site. Minimally invasive surgery has several advantages over other techniques including, inter alia, less trauma to the patient, smaller incisions, less post-operative pain, quicker recovery time (especially in the case of heart surgery since no ribs need to be broken for minimally invasive surgery), shorter time spent in the intensive care unit, as well as other advantages that will occur to those skilled in the art based on the teaching of this disclosure.
The nature of minimally invasive surgery demands several criteria that should be considered for any item used in minimally invasive surgery. This disclosure will focus on fasteners, tools used to place the fasteners, and methods associated with such placement in a minimally invasive surgical procedure. Specifically, this disclosure will focus on fasteners and tools used to place fasteners as well as the techniques for using those tools and fasteners in minimally invasive heart valve replacement surgery. For example, since speed is important for many reasons, the fastener should be capable of expeditious use. However, even though speed is important, the fastener must be capable of reliable and secure placement since a non-secure fastener can have undesirable results, especially if leak-paths could be formed adjacent a non-secure fastener. Still further, any item used for minimally invasive surgery, like any item used for any surgery, should have the confidence of the surgeon. This requires any new item to be useable with techniques and tools that are familiar to the surgeon so he or she need not make large changes in a technique they are already familiar with. It has been observed that surgeons are comfortable in making only incremental changes in technique rather than large scale and sweeping changes in technique. In many minimally invasive procedures, access to the surgical site is of paramount concern. The instrument should be designed to have a minimum bulk and to facilitate action that the surgeon can no longer accomplish with his hands due to restricted access. Since the operation occurs deep inside the patient and the surgeon will have only limited access and visualization of the site, it is important that the tools being used facilitate the procedure as much as possible. In addition, since access is so limited, methods must be effective. There must be a high probability of success in carrying out the techniques for them to be viable and accepted. As mentioned above, heart valve replacement will be used herein as a specific example of a technique that is amenable to minimally invasive techniques. Heart valve replacement using minimally invasive techniques is full discussed in the incorporated applications. While heart valve replacement will be used as the best mode, it is understood that the invention disclosed herein can be used in a myriad of techniques as will occur to those skilled in the art based on the teaching of this disclosure. Accordingly, there is no intention to limit the present disclosure to heart valve replacement only. Still further, the terms "fastener," "anchor" and "staple" as used in this disclosure are intended to be interchangeable. However, those skilled in the art will understand that the term "fastener" can include other elements and a "staple" is a form of fastener. Wire suture is yet another term used to describe the fastener disclosed herein.
As can be understood from the foregoing, there is a need for a means and method for placing fasteners in a minimally invasive surgical procedure that is expeditious but reliable and is small enough to provide a clear sight path and be manipulated by a surgeon in small areas, yet will be secure when placed and will have the confidence of the surgeon.
As disclosed in the incorporated applications, heart valves can be installed with double lead sutures with a pledget and needles on the end of each suture lead. As further discussed in these applications, each suture needle can be independently placed through the annulus of a patient's tissue and the free ends brought up outside the cavity. Pairs of these sutures are placed, according to the teaching of the incorporated material, circumferentially around the annulus where the old valve has been excised. Once all of the sutures are placed, the needles are then passed through the sewing cuff on the prosthetic heart valve. The prosthesis heart valve is then slid down the associated suture into place in the annulus and the knots tied according to the teaching of these disclosures.
In accordance with these disclosures, there is a need for a fastener, tools and methods which can take advantage of the advances disclosed and taught in the incorporated disclosures.
Currently, some companies have been making tools to facilitate suturing of heart valves for minimally invasive procedures. These include modifications of existing needle driver (forceps) technology or devices to hold the sutures in an organizer to help facilitate the procedure. The problem is that a long needle driver needed for the minimally invasive access makes it difficult to manipulate the tools and even more difficult to tie knots at a remote location and there is little time savings realized. Surgeons therefore have had a difficult time replicating their current techniques with subtle improvements to their existing tools when modified for minimally invasive surgery. For instance, when a surgeon places and drives a needle, the path of motion the needle takes through the patient's tissue is on an arc, with the center of the arc determined roughly by the radius of curvature of the needle. In a minimally invasive surgery procedure, one cannot twist the needle driving forceps in the same path as one does when using the "open procedure" instruments. This is due in part to the limited space associated with minimally invasive surgery. Also, this is due to restricted "in-line" viewing which is all one can obtain when viewing down a small and narrow tunnel-like incision used in minimally invasive surgical procedures. In addition, some surgeons may, in some procedures, want control of the number of sutures used and the location of each of those sutures. In other words, the procedure will most likely take longer and require greater surgeon skill than would a standard non-minimally invasive operation. This will hamper the growth of minimally invasive procedures.
Therefore, there is a need for a fastener and tool for placing the fastener that will be readily adopted by surgeons practicing minimally invasive surgery, such as heart valve replacement surgery.
Still further, it is very undesirable for a suture to come out of the tissue or the item being anchored to the tissue. This can be a problem in older patients with brittle or frail tissue. Therefore, the stress (force per unit area) placed on the tissue by any device used to anchor another device to the patient should be as low as possible. This can be achieved by either reducing the amount of force applied to the tissue or by increasing the area of force application. However, this stress reduction must not occur at the expense of a secure anchor and a leak-proof joint. In the case of a heart valve replacement, the fluids present will be pressurized blood, which cannot leak, and in the case of an installation of a prosthesis in the gastro-esophageal tract, the fluids may include bile fluid and other digestive tract contents, also which cannot be permitted to leak. Thus, a leak free joint is essential, but cannot be obtained at the expense of tearing the patient's tissue. Thus, the amount of force applied is not easily reduced.
Therefore, there is a need for a fastener that can increase the total area of force application in an anchor situation without unduly sacrificing other advantages such as a good blood seal between the prosthesis and the patient's tissue.
Yet a further problem with some prosthetic heart valves and the prior implanting procedures associated therewith is that there are unwanted projections remaining on the implanted item. These projections are created when sutures currently used in such procedures are knotted on the implanted item. This is especially true for valves that are sutured in place. Blood clots tend to form around foreign objects in the body. The body's natural defenses try to seal off any foreign material and make it non-threatening. However, there is a danger that the formed blood clots may dislodge into the patient's blood stream which may cause a major problem such as stroke.
The sutures used in many existing techniques to sew a cuff in place are knotted and cut off. This leaves raw edges exposed to the patient's blood stream. These raw edges of the cut-off suture and knot provide surfaces for clot formation and since they are flexible and are directly in the high pressure blood flow path, they provide potential for clots to break off into the bloodstream. Loose clots in the bloodstream are dangerous for the patient as they have the potential for producing a stroke. Clots forming on sutures may also extend into the valve and produce malfunctions by trapping the valve open or shut. It is common practice to treat a post-surgical patient with heparin or some other anticoagulant to minimize the production of clots, short term. For longer term anticoagulant thereby, the patient with a mechanical heart valve prosthesis faces a life long requirement of use of a low grade anticoagulant such as Cumenden.RTM..
Still further, the exposed surfaces can become a site for infection. Circulating bacteria may become attached and lead to infection at the implanted device. Such infections are notoriously difficult to treat with antibiotics.
Therefore, there is a need for a means and method for placing an item, such as, for example, a heart valve, in a patient during minimally invasive surgery that minimizes the amount of foreign objects that remain exposed to the patient after the item has been implanted.
As known to those skilled in the art, prior art sutures require knots. In the case of knots, proper tension is extremely important. Most surgeons determine the tension in a suture knot by feeling the knot with their finger. However, in the case of minimally invasive surgery, the surgeon cannot get his or her hand into position to feel the knot and thus ensure proper tension.
Therefore, there is a need for a fastener that can ensure proper tension in minimally invasive surgery without requiring a surgeon to touch the fastener to make this determination.
Still further, installing multiple suture pairs can be time consuming and can be difficult. Anything that can shorten the time of a surgical procedure can be advantageous. Therefore, there is a need for a fastener that can be quickly placed yet will still permit a surgeon to have great control of the suturing process and pattern, especially the placement of multiple suture pairs.
There is data available which indicates that because the suture is manipulated with the surgeon's gloved hand during the knot-tying process required by prior art procedures, it is susceptible to contamination from pin hole leaks in those gloves. A system which minimizes the direct contact between the surgeon's hand and any of the implanted items will reduce the potential of the development of infection due to contamination.
Therefore, there is a need for a fastener and a means for implanting that fastener which can minimize direct contact between a surgeon's hand and the item being implanted or any component of such implanted items.
Still further, since many patients have variations in size and spacing for the tissue to which an item is being anchored, the surgeon may want to customize the attachment, by, for example, adding fasteners to create just the right spacing and pattern to produce a desired seal for the item.
Therefore, there is a need for a means and a method for placing fasteners which will permit a surgeon to customize the anchoring features of the system.
Still further, some patients have tissue that is thicker than other patient's tissue, or is more fragile than other patient's tissue or the like. If the fastener being used to attach a prosthesis to a patient's tissue has legs that have a predetermined length relative to the base or crown of the fastener, that fastener may be suitable for tissue that has one thickness but not for tissue that has a different thickness. The same situation applies to the amount of tension that is to be applied to the tissue by the fastener. That is, one patient's tissue may be able to withstand more stress than another patient's tissue. Thus, a fastener that is suitable for one patient's tissue may not be suitable for another patient's tissue.
However, the prior art fasteners have legs that are of a preset length. Thus, the surgeon must guess or anticipate what fastener he or she will use in a particular operation,. or change fasteners during the operation. This is cumbersome and inefficient. A need might even arise in which different fastener leg lengths are needed for the same patient during a single operation.
Therefore, there is a need for a fastener that can be customized for each particular patient, and each particular application, and can be altered as necessary during a single operation.